Final answer:
In order to run a delta report in the Visual Business Director, at least two data sources are necessary to facilitate comparison between different data sets.
Step-by-step explanation:
To run a delta report in the Visual Business Director, a minimum of two data sources are required.
This is because delta reports compare different data sets to highlight changes or differences between them. Without multiple sources of data, there would be nothing to compare, making the generation of a delta report impossible.